The UK is lobbying Europe to water down a key energy-saving target despite the fact it will not take effect until after Brexit, according to leaked documents that sparked warnings that energy bills could rise and jobs put at risk.

On the day Theresa May triggered article 50, government officials asked the European commission to weaken or drop elements of its flagship energy efficiency law.

Green campaigners warned that the efforts to undermine the energy efficiency directive were a sign the Conservatives would dilute or abolish European energy and climate policies after the UK leaves the EU.

In the past, the UK has publicly welcomed the targets, which end in 2020, as an important driver for reducing consumer bills and reliance on energy imports.

The European commission wants a binding target of improving energy efficiency 30% by 2030, compared with business-as-usual.

But documents obtained by Greenpeace, dated 29 March, show the UK urging the commission to lower the goal to 27% and make it non-binding on the EU’s 28 members. A more recent version, dated 22 May and seen by the Guardian, shows the UK has maintained its stance.

Hannah Martin, the head of energy at Greenpeace UK, said: “The government is trying to lock the rest of the EU into weaker energy policies, just as we are leaving. The message ministers seem to be sending is that Brexit could trigger a race to the bottom and be used as cover for getting rid of key environmental safeguards.”

The UK is also pushing to drop an obligation on suppliers – including the big six of British Gas, EDF, E.ON, Npower, SSE and ScottishPower – to cut the amount of energy they sell during the next decade.

Under the commission’s plan, energy companies would have to achieve energy savings of 1.5% a year until 2030, using energy efficiency measures. The UK called for the target to be abolished or, failing that, it should no longer be legally binding.

The directive was important for giving companies the long-term certainty to plan their investments, one business group said.

“Seeking to reduce the level of ambition in the directive is entirely counter-productive both environmentally and economically, and completely undermines the UK’s aspirations to maintain a leadership position on climate change,” said John Alker, policy director at the UK Green Building Council.

Roland Joebstl, of the European Environmental Bureau, a network of environmental groups, said the UK’s lobbying could “crash” the European energy efficiency industry and jeopardise jobs.

David Symons, environmental director at consultancy WSP, said: “It’s surprising that the government is lobbying against a measure that is expected to deliver €70bn of additional gross domestic product and 400,000 jobs across Europe by 2030.”

One expert warned the move could push up household energy bills. Joanne Wade, the chief executive of the UK-based Association for the Conservation of Energy, said: “At an EU level, we need a binding target for energy efficiency, to make sure that there is not an over-emphasis on supply-side options which could result in higher energy bills for consumers.”

However, the industry body that represents the big six and other energy suppliers welcomed the stance taken by the UK. “Market-based measures, rather than binding obligations, should be used to drive energy efficiency investment,” said Lawrence Slade, the chief executive of Energy UK.

The EU has said it committed to putting “energy efficiency first” as part of its action on climate change. Miguel Arias Cañete, the EU’s climate chief, has said he was “particularly proud” of the 2030 target.

The Conservative party’s manifesto pledged to improve the energy efficiency of Britain’s draughty housing stock It said it would establish an energy-saving scheme for big industrial companies, because “an energy-efficient business is a more competitive business”.

A government spokesman said: “Any future decisions on energy efficiency policy would be a matter for the next government.”